1. Field of the Invention
The present invention relates generally to a paperboard carton erector capable of preparing a folded carton from a flat blank, and relates more specifically to an automated erector that folds a flat, die-cut blank of laminated paperboard or corrugated paperboard into a tray, which tray can be used for baking, shipping and storing food and other products. The present invention erects shallow, open-top trays having leakproof corner constructions. The design and folding of the blank eliminates the need for gluing, taping and the like to lock the tray's walls in an upright configuration.
2. Description of Related Art
Conventional foldable cartons are well known and are used worldwide in a variety of applications. For example, the packaging industry utilizes a vast number of cartons in which numerous products are packaged for subsequent shipment. Similarly, a variety of automated carton erectors exist for folding cartons. Foldable cardboard carton erector devices are known for setting up folded carton or box blanks, closing their bottom flaps, and sealing the bottom flaps so the carton can be loaded. Many of the cartons folded by a box erector are commonly referred to as slotted boxes or cases known as a RSC (regular slotted case). These cartons are shipped to a packaging company as stacks of flat collapsed blanks for ease of handling and shipment. After arriving at the packaging company, the blanks are placed into a box erecting apparatus, usually located immediately adjacent a packaging machine. Box erectors automatically remove collapsed boxes individually from a magazine and by various mechanisms, move a box to an unfolded open position, immediately after which the erector automatically moves a pair of minor and major closure flaps on the bottom of the box into a closed position so the box, upon reaching the end of the erector, is in a top open position so that any articles to be contained therein can be inserted manually or automatically into the open top of the erected box. Yet these box devices are not entirely suitable, particularly because they are relatively complicated in construction, and require a large amount of floor space.
These types of disadvantages similarly plague conventional tray erecting devices. Automated construction of foldable trays has been limited primarily to the high-speed production of like trays of the same size. For example, six-pack trays with or without a shrink wrap assist are well known and are produced in high speed and great volume. These types of trays are designed to retain the lower portion of the containers by providing a bottom and four secured sides. While these sides may be secured by a binding means like staples, adhesive is conventionally preferred since the tray is thus much more rigid and the possibility of injury to one's hand during emptying is greatly reduced.
The conventional binding method uses a thermally sealable coating on the carton blank. The places that are to be fastened together are coated and heated by hot air, and thereafter these places are subjected to pressure by clamping jaws, clamping rollers or the like. During erection of these types of trays, the sides or flaps are laid one above the other and fastened by the heat and pressure.
Trays also can be erected by hand, versus automatically, although this method requires both more manpower and more floor space than needed with an automated tray erector.
Typical tray construction begins by manipulating a scored flat sheet or blank. While there may or may not be cutouts in the tray blank providing grip assists for lifting the tray, tray blanks generally have cutout portions that provide tabs that are folded to secure end and side walls. Conventionally, the erected tray has the side and end walls of substantially the same height.
In the conventional erection of a rectangular tray-type carton from a flat blank, it is known to fold the end and side wall panels of the carton approximately perpendicular from the bottom panel of the carton, and then to secure those panels in their desired formation by means of folded gussets formed from gusset panels which join the end and side wall panels integrally together.
Foldable paperboard and corrugated paperboard trays have been developed for a variety of uses, and have been found to provide an economical means for storing and transporting a variety of products. For example, disposable concession trays, such as those disclosed by U.S. Pat. No. 4,705,173 to Forbes, Jr. and U.S. Pat. No. 4,757,937 to Maio, et al., have been found to provide inexpensive and disposable containers for transporting food and drink. These foldable paperboard containers are typically fabricated from a die-cut paperboard blank, and can be stored in a flat configuration, in order to minimize space requirements during shipping and prior to their use by the consumer. The paperboard blanks are typically configured in a manner that permits quick and easy assembly into their erected configurations when placed into use. Unless otherwise indicated, the term "paperboard" herein will also include corrugated paperboard.
The nature of paperboard and corrugated paperboard cartons, however, limit their use to post-preparation storage and handling of most food products. For example, typical paperboard and corrugated paperboard are generally inadequate for use during the baking or cooking of food items, as the materials from which they are constructed will burn or char at elevated temperatures. A shallow wall baking tray is disclosed by U.S. Pate. No. 4,632,302 to Manizza.
Moreover, the structural configuration of many known foldable paperboard or corrugated paperboard containers prevents the containers from being utilized in applications where fluid contents are introduced into the container. In particular, the corner construction of many known foldable paperboard or corrugated paperboard containers includes slits or openings in the blank to facilitate the formation of corners or locking panels when the blank is folded into its assembled configuration. Thus, if fluid contents are introduced into the assembled container, the contents will leak from the container.
For example, the Manizza '302 patent shows a folded panel baking tray wherein the tray's corners comprise an open slot between upright sidewalls, resulting from the tray's assembly from a blank having a generally rectangular corner cutout. When the blank of the Manizza reference is foldably assembled to form a shallow tray, adjacent edges of the sidewall panels at this corner cutout form a slotted corner which is incapable of retaining fluid contents. Moreover, the C-shaped or caddie cuts required along the base panel of the Manizza tray present further openings from which fluid contents can leak. It has also been recognized that containers such as that disclosed by the Manizza reference suffer the further disadvantage that gluing of certain panels is necessary to assemble the container. Such gluing results in additional time and expense to assemble the container, and is preferably avoided.
U.S. Pat. No. 4,844,331 to Oldfather discloses another variety of foldably assembled container. This container includes a corner assembly formed by a slit in the die blank that may permit any fluid content to leak. In addition, a slot is cut into the main panel of this assembly near its corner to receive a locking tab for retaining the structure in its assembled configuration. This slot, owing to its location adjacent the floor of the assembled container presents a further point of potential leakage of fluid contents.
U.S. Pat. No. 4,832,257 to Wood shows a paperboard tray having folded corners requiring no cut lines or openings. However, in order to retain this tray in its assembled configuration, it is necessary to adhesively secure the corner assemblies in their upright configuration. The necessity of gluing disadvantageously requires additional time and expense in the assembly of this tray. Also, because the corner assemblies must be glued to retain the tray in its upright configuration, the tray cannot readily be knocked down into a generally flat configuration for more easy access to the contents of the tray, without substantially damaging the tray. Thus, the tray disclosed by this reference is not suitable for applications in which it is desired to periodically disassemble and reassemble the tray. Moreover, the corner assemblies of this variety of tray are typically glued in the assembled configuration at their point of manufacture. Therefore, the blanks cannot be shipped to their point of use in a flat, unfolded configuration.
Therefore, it can be seen that a need yet exists for a compact and efficient automated erector for constructing a paperboard or corrugated paperboard tray container, which tray can be used for baking, shipping and storing food and other products. The tray should be foldably constructed from a flat, die-cut blank, and should enable fluid contents to be contained therein without the use of glue that can liquefy upon heating in an oven.